Electrical resistance



mama June v, 19.3.2,I

UNITED STATES JAIOB RIOTTVOF NWAWES, GERMANY ELEcTRIcAL RESISTANCE Application led October 1, 1928. Serial No. 309,566, `and in Germany October 7, 1927.

' This invention relates to electrical resistances, and more particularly to that type of resistance which substantially comprises a column or pile of superimposed carbon discs. Electrical resistances of the kind in question have the power of greatly varying their ohmic value under varying pressure. In order to obtain the greatest possible amount of lay in the extent of resistance introduced luy the apparatus the mechanism causing the varying pressure to be applied requires on `the one hand to distribute the-pressure equally over the entire cross-section of the pile or column, while at the same time the same must be capable of relieving the column entirely.v These requirements necessitate a position of. the pressing faces of the mechanism exactly parallel to the -end faces of the column, and are, particularly in the case of a large cross-sectlon of the column, only capable of being fulfilled with 'an exactitude of `construction jvhich is relatively expensive.

Adaptation of the one or both pressing faces to the end faces of the column or pile might be effected in the known manner by furnishin the pressure members with ball joints. T is, however,fisfassociated with the disadvantage that the freely movable pres sure members, in accordance with the particular arrangement, may have the tendency to tilt or otherwise assume an incorrect position when nolonger exerting pressure on the pile of carbon.

The subject matter of the present inventhe ressure members, on the one hand, are capa le of exactly adapting themselves to the end facesof the pile, while on the other j tion is an arrangement by means of which movabi the pile when the amount.

The invention will now be described more `fully with reference to the accompanying drawing, in which j Figs. 1 and 2 show twopossible forms of embodiment.

Referring to Fig. 1, A represents the pile or column -of carbon discs, and B a lever, which is acted upon by the force C and compresses the pile A to a greater or lesser extent. D is the one pressing face which, vaccordin to the invention, is connected in movab e manner to the lever B, the same in the case of the present embodiment bein rotary about the ball E in the cu F. gince the member D due to its unstable position might have the tendencyto tip over, and consequently, when thecolumnor pile were wholly relieved, assume together with the column a tilted position, so that the upper end of the column would not be released, the ball E is according to the invention furpressure exceeds a certain l I' nished with a friction device consisting of a sheet metal'ring G and pressure lscrews J. By means thereof the plate D is maintained in its normal relative position to the lever B, while on the other hand the friction at the ball E is nevertheless suiliciently small that adjustment is possible in relation to the face of the column upon the application of reasonable pressure.

Adjustability by meansoffriction of the one pressing face of the mechanism is of particular importance if in place of onecolumn or pile A two or more are arranged side by side and are simultaneously acted upon by the same pressing faces D and K.

Fi 2 showsa form of embodiment in whic two columns or groups of columns A are acted upon by two different, movable pressing members. In such an instance it is desirable to also connect the beam B distributin the pressure to the two columns A mova ly with the pressure members M, the

vity likewise being limited in suitable manner. This is necessary in order upon, difference in wei ht on the two sides to prevent the unstable am from tipping towards the one side. For thispurpose the pressure y.

'members M are furnished with a friction means E similar to that in the case of the first embodiment. In this manner the pressure C, on the one hand, is distributed per- 5 fectly evenly over the two columns A, while on the other hand a tipping of any of the parts, which would make complete relief of the columns impossible, is prevented.

What I claim as new and desire to secure 1 by Letters Patent is: n

l. In a form of embodiment of an electrical resistance, a pile of carbon discs constituting the resistance proper, a lever for a plying varying pressure to the said ile, a p ate resting against one end of the said pile, a ball joint between the said plate and the said lever so as to enable the said plate to adapt itself to the said pile, and a frictionl means provided at the said joint in order to 2 restrict the free movability of the plate.

2. In a form of embodiment of an electrical resistance, a plurality of piles of carbon discs situa-ted side by side, means for applying varying pressure to the said piles, a beam for distributing the said pressure equally over the said piles, plates resting against the ends of the said piles, connectlng niembers between the sai plates and the said beam, joints between the said plates and the said connecting members, joints between the said beam and the said connecting members, and friction means at the said joints in order to restrict the free movability of the plates.

3. Apparatus according to claim 1 in which said friction means are adjustable. In testimony whereof I have ailixed my signature.

JAKOB RIOTTE. 

